package com.dragon.utilslibrary.tools;

import android.util.Log;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 生成md5工具
 */
public final class MD5Util {

    private static char hexDigits[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
    private static MessageDigest messageDigest = null;

    private MD5Util() {

    }

    static {
        try {
            messageDigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            Log.d("MD5Util", MD5Util.class.getName() + "初始化失败，MessageDigest不支持MD5Util.");
            e.printStackTrace();
        }
    }

    /**
     * 计算文件的MD5
     *
     * @param fileName 文件的绝对路径
     * @return
     * @throws IOException
     */
    public static String getFileMD5String(String fileName) throws IOException {
        File f = new File(fileName);
        return getFileMD5String(f);
    }

    /**
     * 计算文件的MD5，重载方法
     *
     * @param file 文件对象
     * @return
     * @throws IOException
     */
    public static String getFileMD5String(File file) throws IOException {
        FileInputStream in = null;
        try {
            in = new FileInputStream(file);
            FileChannel ch = in.getChannel();
            MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0, file.length());
            messageDigest.update(byteBuffer);
            return bufferToHex(messageDigest.digest());
        } finally {
            if (in != null) {
                in.close();
            }
        }
    }

    private static String bufferToHex(byte bytes[]) {
        return bufferToHex(bytes, 0, bytes.length);
    }

    private static String bufferToHex(byte bytes[], int m, int n) {
        StringBuffer stringbuffer = new StringBuffer(2 * n);
        int k = m + n;
        for (int l = m; l < k; l++) {
            appendHexPair(bytes[l], stringbuffer);
        }
        return stringbuffer.toString();
    }

    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
        char c0 = hexDigits[(bt & 0xf0) >> 4];
        char c1 = hexDigits[bt & 0xf];
        stringbuffer.append(c0);
        stringbuffer.append(c1);
    }

    public static String MD5(String AESEncryptString) {
        byte[] hash;
        try {
            hash = MessageDigest.getInstance("MD5").digest(AESEncryptString.getBytes("utf-8"));
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
            return null;
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            return null;
        }
        Log.i("MD5Utils", "md5=" + toHex(hash));
        return toHex(hash);
    }

    private static String toHex(byte[] buf) {
        if (buf == null)
            return "";
        StringBuffer result = new StringBuffer(2 * buf.length);
        for (int i = 0; i < buf.length; i++) {
            appendHex(result, buf[i]);
        }
        return result.toString();
    }

    private static void appendHex(StringBuffer sb, byte b) {
        final String HEX = "0123456789ABCDEF";
        sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
    }

    public static void main(String[] args) throws IOException {
        String fileName = "E:\\lyyy.flv";
        long start = System.currentTimeMillis();
        Log.d("MD5Util", getFileMD5String(fileName));
        long end = System.currentTimeMillis();
        Log.d("MD5Util", "Consume " + (end - start) + "ms");
    }

    public static String getMD5(String info) {
        try {
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(info.getBytes("UTF-8"));
            byte[] encryption = md5.digest();

            StringBuffer strBuf = new StringBuffer();
            for (int i = 0; i < encryption.length; i++) {
                if (Integer.toHexString(0xff & encryption[i]).length() == 1) {
                    strBuf.append("0").append(Integer.toHexString(0xff & encryption[i]));
                } else {
                    strBuf.append(Integer.toHexString(0xff & encryption[i]));
                }
            }
            return strBuf.toString();
        } catch (NoSuchAlgorithmException e) {
            return "";
        } catch (UnsupportedEncodingException e) {
            return "";
        }
    }

}
